1. Field of the Invention
The present invention relates to a buckle of an insertion type having a housing-shaped buckle body and an insertion member including a leg portion formed by a projection piece for an insertion, and particularly to a buckle for a belt which is generally used in clothes, bags, helmets or sporting goods.
2. Description of the Related Art
As shown in FIG. 15, there has conventionally been known a buckle of an insertion type having a housing-shaped buckle body 101 and an insertion member 151 including an insertion leg portion 153. The insertion member 151 is provided with an insertion leg portion 153 on one of the ends of a board 155, in which a projection-shaped engaging portion 157 is provided on both sides of the tip of the insertion leg portion 153, and furthermore, an operating portion 159 overhung toward the side is provided on outside surfaces at both sides of the leg portion. The buckle body 101 is formed by a flat cylindrical box 103 as a whole, in which an insertion port 105 is provided on one of ends and an opening portion 107 cut like a circular arc is provided on outside surfaces at both sides, a projection-shaped engaging portion 157 is provided on both left and right sides of internal surfaces at both sides. When the insertion leg portion 153 is inserted, the engaging portions of the insertion member 151 and the buckle body 101 are respectively engaged, and disengagement can be carried out by pressing the operating portion 159 (for example, see Japanese Utility Model Registration No. 2533866).
As shown in FIG. 16, moreover, there has been known a buckle having a first fixing member 201 and a second fixing member 213. The first fixing member 201 has a base portion 221 having a belt attachment hole 223 on one of ends and a cover member 211 having a U-shaped section which includes a pair of engagement projections in an inner part and an engagement hole 207 provided on the tip side of the engagement projection to fit and engage the engagement piece of a horn, and both sides and a front surface which are opened. The second fixing member 213 has a horn 217 provided with an engagement piece 209 which has a circular arc portion bulged outward which can be engaged on the inside with the engagement projection of the cover member 211 on the outside surface of a tip at the front surface of the base portion 203 having a belt attachment hole 215 on one of ends and has a connected portion 205 protruded outward like a hook. The second fixing member 213 is engaged with the opening of the cover member 211 by fitting an insertion engagement piece 209 in the engagement hole 207, and furthermore, a wide press plate 219 having a T-shaped plane is provided on the outside of the center of the horn 217 and the fitting and engaging operation of the engagement hole 207 and the engagement piece 209 can be released by pressing the press plate 219 (for example, see JP-B-55-23601).
Japanese Utility Model Registration No. 2533866 (especially, pages 2 and 3, 0012 to 0015, FIGS. 1 to 4) and JP-B-55-23601 (especially, pages 1 and 2, FIGS. 1 to 6) are known as reference documents.
The buckle for inserting the insertion member into the buckle body, which is disclosed in Japanese Utility Model Registration No. 2533866, has such a configuration that a pair of insertion leg portions 153 provided in the insertion member 151 are prism-shaped and the engaging portion 157 is provided on both sides of a tip, the operating portion 159 protruded from the opening portion 159 of the buckle body 101 is provided in an outer part on the inside of the engaging portion 157, and the leg portion between the operating portion 159 and the board presses the operating portion 159 to carry out an elastic deformation so that the engaging portion 157 of the tip and the engaging portion 157 are disengaged. In order to carry out a smooth engaging/disengaging operation, the elastic deformable part of the leg portion is formed to be long or thin. The size of the buckle has to be increased so as to form the elastic deformable part to be long. For this reason, it is impossible to obtain a small-sized buckle having a good appearance. As a result that the elastic deformable part of the insertion leg portion 153 is formed to be thin, a problem that the thin portion is firstly broken might occur.
In the buckle for inserting the horn of the second fixing member into the cover member of the first fixing member, which is disclosed in JP-B-55-23601, it is necessary to easily carry out the elastic deformation of the horn 217 in a section provided with the press plate 219 from the base portion 203 of the horn 217 in order to smoothly remove the engagement piece 209 from the engagement hole 207 of the engagement projection provided on the cover member 211 by pressing the press plate 219 having a T-shaped plane which is provided on the horn 217 of the second fixing member 213. Accordingly, as this section cannot be shortened, the size of the buckle is increased because of the long shape and the easy elastic deformation. Moreover, since the cover member 211 has a U-shaped section in which the side surface is opened, corners on both sides of the double-sided plate of an open edge in the opening are exposed. In use, therefore, the cover member is caught on other things so that a smooth operation cannot be carried out. In the case that a twist acts on the double-sided plate in an inserting operation, moreover, there is a problem that a breakage might be caused.